Messenger

A delegate-based event messenger system built for Unity projects. This work is a direct rewrite of CSharpMessenger Extended which was posted to the Unify Community Wiki back in its day. The initial work was authored by Magnus Wolffelt, with Rod Hyde quotations, and Julie Iaccarino.

Usage

The following code samples are designed to be ran within a MonoBehaviour derived class; as can be seen with the use of Unity reserved method names.

Adding an event listener

Each listener must be registered within the class OnEnable method. For these examples, we are assuming one argument will be sent with each broadcast.

private void OnEnable() 
{
    Messenger<float>.AddListener("PlayerDamaged", OnPlayerDamaged);
}

Removing an event listener

In like, each listener must be cleaned up and removed within the class OnDisable method.

private void OnDisable()
{
    Messenger<float>.RemoveListener("PlayerDamaged", OnPlayerDamaged);
}

Writing your event listener

There are no rules imposed by the messenger on how the method must be writen, save for the signature must match what was registered.

private void OnPlayerDamaged(float amount)
{
    PlayerHealth -= amount;
}

Broadcasting to your listeners

When calling the Broadcast function, you again must make sure that signatures match what was registered.

private void Attack()
{
    [...]
    Messenger<float>.Broadcast("PlayerDamaged", 5f);
}

Additionally the messenger will default to broadcasting using MessengerMode.REQUIRE_LISTENER mode. This is as it sounds, and requires that any event broadcast has at least one listener. A BroadcastException will be thrown otherwise. This can be circumvented by specifying the mode in your Broadcast call.